Mild appearance notwithstanding, this well-scrubbed 30-year-old has slogged through a pretty harrowing half decade. Six years ago, he was frontman for one of the country’s biggest bands, the author of the polished alt-pop hits ”Buddy Holly,” ”Undone — the Sweater Song,” and ”Say It Ain’t So.” Three years later, Cuomo suffered something of a breakdown, holing himself up in a depressing Los Angeles hideout while his life and career seemed indefinitely derailed.

Now Weezer, his band, are back in a big way. They’ve touched down in this moneyed golf-and-tennis mecca to co-headline the Coachella Valley Music and Arts Festival, a one-day concert featuring Jane’s Addiction, Fatboy Slim, and more than 40 other acts, which has just kicked off on an immaculately manicured polo field in nearby Indio, Calif. A new album (self-titled but referred to as the Green Album) hit stores May 15. The first single, ”Hash Pipe,” is already climbing the charts, and its sumo-wrestling-themed video is shaping up to be an unlikely TRL hit amid the teen pop and rap-metal clogging the show’s playlist. And the band’s fan base — which somehow became more fanatical the longer Weezer were away — is on the brink of a major growth spurt.

Seated in his room’s kitchenette, Cuomo, killing time several hours before Weezer are set to take the stage, is at a loss to explain his group’s comeback. An awkward, introverted guy with an intense distaste for talking about himself, he in fact seems reluctant to explain much of anything, and piecing together events of the past six years is no easy task. His most common response to even innocuous questions is an icy stretch of silence followed by a deliberately cryptic answer. (”I don’t answer ‘why’ questions,” he declares at one point. How come? ”That’s a ‘why’ question.”)

Slowly, however, the story emerges. Most fans lost track of Weezer after the release of 1996’s Pinkerton, the flop follow-up to their self-titled, triple-platinum debut (known as the Blue Album). ”That’s where I lost track too, unfortunately,” Cuomo says, staring glumly at his knuckles. The confessional, self-flagellating album was widely slammed as crude and indulgent, an ego trip from a novelty act that should have faded away gracefully. ”Everybody hated it,” says Cuomo. ”Critics, the majority of our fans, most of my friends and family, the other band members….Everyone thought it was” — he pauses, letting the thought hang — ”an embarrassment. One of the worst albums of all time.”

For a kid who grew up in the tiny Connecticut town of Yogaville dreaming of Kiss-style rock stardom, the rejection was agonizing. Cuomo’s downfall was as sudden as his rise to fame — Weezer formed in Los Angeles in 1992 and signed a major label deal after only a few months of local club gigs — and it’s an experience Cuomo obviously doesn’t like to dwell on.